1. Field of the Invention
The invention relates to vacuum cleaners. In one of its aspects, the invention relates to vacuum cleaners having cyclonic dirt separation. In another of its aspects, the invention relates to an improved filter cartridge for a vacuum cleaner.
2. Description of the Related Art
Upright vacuum cleaners employing cyclone separators are well known. Some cyclone separators follow textbook examples using frusto-conical shape separators and others use high-speed rotational motion of the air/dirt to separate the dirt by centrifugal force. Typically, working air enters and exits at an upper portion of the cyclone separator as the bottom portion of the cyclone separator is used to collect debris. Furthermore, in an effort to reduce weight, the motor/fan assembly that creates the working air flow is typically placed at the bottom of the handle, below the cyclone separator.
BISSELL Homecare, Inc. presently manufactures and sells in the United States an upright vacuum cleaner that has a cyclone separator and a dirt cup. A horizontal plate separates the cyclone separator from the dirt cup. The air flowing through the cyclone separator passes through an annular cylindrical cage with baffles and through a cylindrical filter before exiting the cyclone separator at the upper end thereof. The cyclonic dirt separator comprises a dirt tank wherein fins project vertically from a sidewall to reduce re-entrainment of dirt particles, as is further disclosed in the U.S. Pat. No. 6,810,557, which is incorporated herein by reference in its entirety.
U.S. Patent Application Publication No. US 2008/0047091 to Nguyen discloses an upright vacuum cleaner with a cyclone separator, dirt cup, and vortex stabilizer.
U.S. Pat. No. 4,571,772 to Dyson discloses an upright vacuum cleaner employing a two stage cyclone separator. The first stage is a single separator wherein the outlet of the single separator is in series with an inlet to a second stage frusto-conical separator.